Lymphoma In Dogs

Lymphoma In Dogs: Causes, Symptoms, and Treatment

If your pet has been diagnosed with lymphoma, there are likely a million questions racing through your head. Any threat to your pet's health can cause a great deal of distress and emotional turmoil. Fortunately, there are treatments available. In this article, we'll cover everything you need to know about the various forms of lymphoma, what treatment options there are, and how you can help improve your dog's fight against this disease.


What Is Lymphoma In Dogs?

Lymphoma is a cancer that affects your dog's lymphatic system. The term covers a somewhat broad group of cancers. The kind of lymphoma that your dog has will determine their treatment, symptoms, and diagnosis.

Lymphoma cancers are derived from white blood cells in your dog known as "lymphocytes." These white blood cells, under normal conditions, are a part of your dog's immune system and work to keep their health in top shape. Because of this, lymphoma is most likely to affect an organ that is a part of your dog's immune system. Lymphoma can affect any area of your dog's body, however. The most commonly affected areas are your pet's lymph nodes, spleen, and bone marrow.

Unfortunately, lymphoma is one of the most common cancers that canines develop. It's very similar to lymphoma in humans, and the treatment prescribed for dogs is usually pretty close to the treatment prescribed to people. While there are some cases of passive and slow lymphoma development, it usually spreads throughout a dog's system rather quickly and should be treated as soon as possible to improve your dog's chances of beating the disease.


Are Dogs With Lymphoma In Pain?

Lymphoma itself is not believed to be painful in dogs, even when the affected areas and tumors become large in size. However, because lymphoma weakens your dog's immune system, they can become more susceptible to illnesses, leading to more complicated health issues over the course of the disease.


Types Of Lymphoma

There are over 30 different forms of canine lymphoma, each with a different prognosis, set of symptoms, and rate of progression. The kind of lymphoma that your dog is diagnosed with will determine how your vet decides to treat the issue.

While there is a large variety of lymphoma-cancers, there are five that are much more common than the rest:


Multicentric Lymphoma

The most common form of lymphoma in dogs by far is multicentric lymphoma. As much as 80% to 85% of canine lymphoma cases are multicentric. This form of lymphoma affects the dog's lymph nodes and is most easily spotted by the masses that grow on these areas.

The affected areas can grow up to ten times their normal size, making it more obvious than the other types. While these masses may look painful, they generally don't cause any pain for your pet. Even though less pain may seem like a good thing, it actually makes a diagnosis that much harder, since you will have to notice it without any clear indications from your pet.

Not only does multicentric lymphoma weaken your pet's immune system, but it can spread to other healthy organs, eventually leading to organ failure.


Symptoms of Multicentric Lymphoma

The telltale sign for multicentric lymphoma in dogs is the painless swelling of the lymph nodes. Hepatosplenomegaly might also occur, which is the enlargement of the spleen and liver. It is also common for your pet's bone marrow to be affected as well.

Aside from this, most dogs with multicentric lymphoma do not give any other indications of the disease. However, in some cases, dogs may exhibit anorexia, weight loss, ascites (accumulation of fluid in your pet's abdomen), difficulty breathing, excessive thirst or urinating, fever, anemia, hemorrhages, and inflammation throughout the body.

Multicentric lymphoma can develop into central nervous system lymphoma in later stages, causing seizures, paralysis, or loss of movement.


Alimentary Lymphoma

Alimentary lymphoma, also known as gastrointestinal lymphoma, occurs in the digestive tract of dogs. It's the second most common form of lymphoma in canines, accounting for a little less than 10% of lymphoma diagnoses. Alimentary lymphoma can become fatal if it affects the small or large intestine since this can obstruct the passage of your pet's bowels. This can lead to serious and complicated health risks for your pet.


Symptoms of Alimentary Lymphoma

Symptoms of Alimentary LymphomaGastrointestinal lymphoma can be contracted by a large variety of breeds and ages of dogs, although it is more common in male dogs than female dogs.Because the symptoms are primarily in your dog's digestive tract, it's more difficult to diagnose than multicentric lymphoma. The most obvious clinical signs of a dog with alimentary lymphoma are vomiting, weight loss, diarrhea, excessive urinating or thirst, anorexia, lethargy, and malabsorption (a reduced ability for your dog's digestive system to pull nutrients from their food).


Mediastinal Lymphoma

Mediastinal lymphoma is a fairly rare form of lymphoma. It develops in the lymphoid tissues of a dog's chest, primarily around their cardiothoracic region. Areas like the thymus or mediastinal lymph nodes can become enlarged, restricting your dog's ability to breath. If untreated, this restriction could eventually lead to your dog's lungs not functioning properly, resulting in fatal consequences.


Symptoms of Mediastinal Lymphoma

The signs of mediastinal lymphoma are usually fairly obvious since the affected areas are prominent. The most common symptoms involve swelling of the cranial mediastinal lymph nodes, thymus, or both. It can also cause pitting edema (swelling and abnormal growth) of your pet's head, neck, and front legs. Dogs suffering from this disease will likely have difficulty breathing and excessive thirst or urination.


Cutaneous Lymphoma

Cutaneous lymphoma affects your dog's skin, and will usually look like red, itchy lumps across your pet's body. It should be fairly noticeable, especially since it causes a great deal of discomfort for your pet. The main difficulty is recognizing that it is a form of lymphoma, and not just another rash or the result of bug bites.


Symptoms of Cutaneous Lymphoma

Cutaneous lymphoma will usually look like itchy, red bumps across your dog's skin, but it can also take the form of ulcers, plaques, nodules, and erythremic or exfoliative dermatitis. In the early stages of cutaneous lymphoma, it will most likely manifest as a severe skin rash, with symptoms like scaling of the skin, hair loss, and excessive itchiness. As it becomes more severe, the skin will become more rash-like, thickened, ulcerated, and might even ooze fluids. The disease could also affect your dog's mouth, causing ulcers, lesions, and nodules on your pet's gums and lips.


Extranodal Lymphoma

Extranodal lymphoma is the rarest form of the disease. "Extranodal" means that it targets a specific organ in your dog's body, most commonly the eyes, kidneys, lungs, skin (cutaneous lymphoma), and central nervous system. Other areas that can be affected include the breast tissue, liver, bones, and mouth.


Symptoms of Extranodal Lymphoma

Because it can affect such a wide range of areas in your dog's body, the symptoms are not very cut and dry. The only real way to catch it is to notice that a certain area of your dog's health is deteriorating, i.e. loss of vision, difficulty breathing, skin rash, etc.


What Causes Lymphoma In Dogs?

Just like with any type of cancer, the causes behind it in humans and dogs alike are relatively unknown. Scientists are actively engaged in advanced genetic studies to determine the cause of lymphoma in canines, but there is still a ways to go before we know the source for sure. Currently, it is believed that, like in humans, there is a mix of complex genetic and environmental factors that can lead to the development of lymphoma in our pets. Because dogs are exposed to the same environments that we are, the likelihood of a pet developing cancer is similar to the chances of a human developing it. There are also some dog breeds that are more predisposed to developing lymphoma than others.

Because the exact cause of lymphoma is not known, the following are mostly speculative ideas within the scientific community.


Toxic Environment

Environmental causes are believed to play a significant role in the development of cancers. Since everyone has such varied genetics and lifestyles, the environment is a probable cause due to its universality. Whether you are aware of it or not, your day-to-day environment is full of harmful toxins that can impact your health over a long period of exposure.

Paints, solvents, pesticides, herbicides, and insecticides are all believed to be harmful to your health with frequent exposure. Factors like viruses, bacteria, chemical exposure, and strong magnetic fields have also been considered by scientists as factors behind lymphoma development. Because most dogs spend a lot of time outside, they are likely to come into contact with these elements on a regular basis. Dogs that live in industrial areas could also be at a higher risk for developing lymphoma.


Breeds At Risk For Developing Lymphoma

Certain breeds are at a higher risk of developing lymphoma, although the underlying cause as to why this is the case is still unknown. Changes in the structure of chromosomes, for example, are thought to be a cause of the disease. So, dogs with a higher predisposition for abnormal chromosome development would be (possibly) more likely to develop some form of lymphoma.


The Following Breeds Have A Higher Chance of Developing Lymphoma:

  • Rottweilers
  • Scottish Terriers
  • Basset Hounds
  • Airedales
  • Saint Bernards
  • Golden Retrievers
  • Bullmastiffs
  • Boxers
  • Bulldogs


Just like some dogs are more likely to develop lymphoma, some are less likely. In particular, dachshunds and Pomeranians are not as likely to develop canine lymphoma. The disease is also most common in middle-aged dogs (ages 6 to 9). That being said, any breed can develop this form of cancer at any age, so always be on guard and proactive about your pet's health. The best way to keep your dog safe is to make sure that you are fully aware of the symptoms, monitor your dog's health frequently, and take them for regular check-ups at your local vet.


Is Lymphoma Preventable?

Because the exact cause of lymphoma in dogs is still unknown, there is no set way to prevent it from occurring. However, there are still some measures you can take to decrease the chances of your pet contracting the disease.

For one, try to avoid using pesticides and herbicides in your yard as much as possible. A study found that dogs from pet owners in households that frequently sprayed 24-D herbicides around their property had a much higher chance of developing a malignancy. There is also believed to be a link between the development of cancer and frequent use of chemical-based paints. Keeping your dog away from these kinds of materials will help reduce the chance of your pet developing lymphoma.


Most Common Symptoms Of Lymphoma In Dogs

While each form of lymphoma has slightly different symptoms from each other, there are some general symptoms to be on the lookout for that can indicate lymphoma in your pet.


Even though the affected areas may be different, swelling is the most obvious symptom to be on the lookout for. The most common parts of your dog's body to swell are their lymph nodes. They have lymph nodes located under their jaw, in front of their shoulders, and behind their knees. Swollen lymph nodes will feel like rubbery, hard lumps under your pet's skin. While they aren't painful, these are serious signs of lymphoma development, and vet intervention should be sought after immediately.

Other areas that are likely to swell include your pet's face and legs. They might also develop severe rashes and other skin conditions as well.


Unusual Behavior/Health Condition

Another easy way to determine if your dog is developing lymphoma is to monitor their standard routine closely. Animals don't usually go out of their way to deviate from their normal habits, so if you notice a change in your pet's behavior, there is likely an underlying cause.

Changes in eating habits, drinking habits, bathroom habits, or energy levels could all be signs of lymphoma or another serious health condition. Always consult with your vet when you begin to notice unusual and unexplained behavior in your dog.

Diagnosing Dogs With Lymphoma

Lymphoma is not the only health condition that can cause your dog's lymph nodes to be enlarged, so swelling of these areas does not guarantee your dog has this disease.

To determine the cause of your dog's enlarged lymph nodes, your vet will most likely conduct an aspirate on the affected areas. This means they will take a fine needle and use it to extract a few cells from the affected node. These will then be analyzed to determine the exact cause of the issue.

If the aspiration is inconclusive or too difficult to perform on the affected area, your vet will likely opt to perform a biopsy. This involves a minor surgical procedure with the goal of removing a sample of the damaged tissue. A standard bloodwork screening, which involves taking a complete blood count from your dog, will be conducted as well to check for other abnormalities in your pet's condition.

If your dog is diagnosed with lymphoma, then your vet will perform additional tests to determine how severe it is, which stage it is in, and which form of the disease that your pet has. These tests involve distinguishing if your pet's lymphoma has resulted in B-cells or T-cells, as well as imaging tests like X-rays and ultrasounds to assess the extent of the disease.

The Five Stages Of Lymphoma In Dogs

The are five stages of lymphoma in dogs according to the World Health Organization. An important part of the diagnosing process is to determine which stage of lymphoma your pet is in. This helps your vet understand which form of treatment will be most effective, and how likely your pet is to recover.


The Five Stages of Lymphoma in Canines:


  • Ailment limited to a single lymph node
  • Regional lymphadenopathy, meaning the ailment is restricted to one side of your pet's diaphragm
  • Generalized lymphadenopathy, meaning the lymph nodes are enlarged
  • Hepatosplenomegaly, meaning the liver and spleen are enlarged; this is considered Stage 4 whether lymphadenopathy has taken place or not
  • Involvement of extranodal areas like your dog's bone marrow or central nervous system

Treatment For Dogs With Lymphoma

While there is no cure for canine lymphoma yet, the most effective treatment is chemotherapy. The kind of chemotherapy your vet recommends will depend on which form of lymphoma your dog has. Radiation therapy or surgery might also be suggested if your vet believes it will help.

Dogs generally tolerate chemotherapy much better than people do. Only a few breeds lose their hair from the treatment (poodles, Old English sheepdogs, Bichon Frise, and a few others), and the symptoms are fairly mild. The most common side effects your dog will have during chemotherapy are mild vomiting, diarrhea, decreased appetite, and lethargy.

Dogs can also become dehydrated from lymphoma, which requires fluid therapy alongside chemo. In other cases, fluids might accumulate in your dog's chest or abdomen, which will need to be removed by your vet. Even those chemotherapy and other treatments help slow down the disease's effects, they are not a cure, and relapse is fairly common in dogs with lymphoma. The best you can do for your pet is to keep the quality of life as high as possible through treatment and careful monitoring.


Prognosis For Dogs With Lymphoma

Sadly, like any cancer, the prognosis for dogs with lymphoma isn't very uplifting. Because there is no known cure, dogs can only ever reach remission. There are two types of remission: total and partial. Total means that all symptoms and signs of cancer have been removed from your pet's body. This does not mean, however, that the cancer has left their body, only that it has been treated into dormancy. Partial remission is when most, but not all, signs and symptoms of lymphoma are no longer present in your pet.

In either case of remission, there is always the chance that the cancer will come back. And each time it comes back, it will be more difficult to get your pet back into remission. Eventually, unless your dog passes away from other causes (like old age) lymphoma will be fatal. The most important thing you can do is keep their quality of life high and work closely with your vet to improve your dog's odds of reaching remission.


Using CBD Oil For Lymphoma In Dogs

One approach that you can take (alongside traditional lymphoma treatment) is using cannabidiol products during your pet's treatment. CBD products are an all-natural way to counter the negative side effects of chemotherapy without disrupting your pet's health further. CBD is a natural supplement that helps regulate your pet's health, mood, appetite, and sleep. It also reduces inflammation and nausea, two side effects of chemotherapy.

There have also been studies conducted that show CBD may be able to kill cancerous cells. While you should never use it in place of regular, vet-approved treatment, it can be used adjacently to improve their levels of comfort and possibly help your pet reach remission. There aren't any negatives to CBD oils and plenty of potential benefits, so consider speaking with your vet about incorporating CBD products into their treatment.



Lymphoma is one of the more severe health issues your dog could encounter throughout their lifespan. It can also be incredibly difficult to spot, so don't blame yourself for not catching sooner. It's a devastating illness, but with proper treatment and care from your vet, your dog can still lead a comfortable and fulfilling life.



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